A conventional battery-cell module structure of a battery includes a metal container main body and a metal lid to be constructed as a battery accommodating case that has air permeability to communication between an interior and an exterior of the case, where the metal container main body is formed with an opening at-least one side thereof and contains a flat-type assembled battery in which thin batteries are piled up, and the metal lid closes the opening of the metal container main body. A peripheral end portion of an opening end portion of the metal container main body and a peripheral end portion of an end portion of the metal lid are rolled and caulked with each other to construct the battery-cell module structure (For example, refer to Patent Document 1).
Patent Document 1: Japanese Patent Application Laid-Open Publication No. 2006-92884 (page 2-8 and all of Figures)